a. Field of the Invention
The invention relates to fiber optic light energy delivery apparatus and more particularly to an endoscope having a plurality of output tips for selectively converging or diverging light energy.
b. Prior Art
Fiber optic single fiber light energy transmission lines for use in surgical applications are known. For example, U.S. Pat. No. 3,858,577 shows a flexible endoscope with fiber optic fibers transmitting light energy from a laser to a distance output end. The article entitled "Laser-Induced Hemostasis in the Canine Stomach" by Dwyer et al. in JAMA, Feb, 3, 1975, Vol. 231, No. 5, p. 486 describes a surgical application for a flexible fiber optic delivery system.
One of the problems which existed in the past was that blood or other debris would occasionally impinge upon the output aperture of the fiber optic fiber. Often light energy would be absorbed by the blood or debris and cause intense local heating of the fiber, sometimes deforming the fiber at its output aperture. To solve this problem, pieces of glass larger in diameter than the fiber optic fiber have been adhered to the fiber for lowering the energy density of light emerging from the fiber thereby limiting the amount of local heating which can occur in any one place.
Energy density may be lowered in a tapered fiber such as shown in U.S. Pat. No. 3,843,865, but a tapered fiber allows little adjustment of beam spot size once a particular taper is selected. In the aforementioned U.S. Pat. No. 3,858,577 different thicknesses of glass may be placed in front of a fiber output aperture, but in achieving small beam spot sizes, localized heating may occur in the glass and may damage the glass and the fiber.
It is an object of the present invention to devise a means for terminating a fiber optic transmission line which avoids localized heating of the light output region, yet which allows selection of a convergent beam or a divergent beam transmitted from a fiber optic fiber.